Transcription, translation and point mutations

BiologyGeneticsAges 17–18

From a gene's template strand, RNA polymerase builds mRNA one nucleotide at a time by base-pairing (A–U, T–A, G–C, C–G); the ribosome then reads each codon from AUG, and tRNA delivers the matching amino acid according to the standard genetic code until a stop codon is reached. Students step through each stage, click a nucleotide to cause a substitution, insertion or deletion mutation, and compare the polypeptide chain before and after (silent, missense, nonsense, frameshift).